Natural essential oils as reducing agents of peroxidase activity in leafy vegetables

The effectiveness of natural essential oils eucalyptus (Eucalyptus globulus), tea tree (Melaleuca alternifolia), melisa (Melissa officinalis), roomer (Rosmarinus officinalis), clove (Syzygium aromaticum) and lemon (Citrus limonum) to reduce peroxidase activity of organic leafy vegetables extracts was evaluated. Three oil concentrations at the minimum inhibitory concentration (MIC, 2×MIC and 4×MIC) of each natural essential oils were used. Crude vegetable extracts of Swiss chard, spinach, lettuce, butter lettuce and cabbage were the source of peroxidase activity. The effectiveness of the essential oils as natural antioxidants varied with the enzyme sources. At the MIC, clove, rosemary, lemon, melisa and tea tree had the high antioxidant properties being clove more effective than the other oils.     

Major chemotypes and antioxidative activity of the leaf essential oils of Cinnamomum osmophloeum Kaneh. from a clonal orchard

Essential oils of 92 cutting clones from a clonal orchard of Cinnamomum osmophloeum Kaneh. were obtained by hydrodistillation and characterised by gas chromatography–mass spectrometry. Our results showed that the yields of essential oils ranged between 0.09% and 2.65% (vol/fresh wt). The constituents of essential oils varied among samples. The major chemotypes classified in the individual cutting clones were cinnamaldehyde (50 plants, representing 50–95% of the total volatiles), linalool (1 plant, 73.3%), β-cubebene (2 plants, 59.4% and 78.7%), and cinnamyl acetate (1 plant, 61.8%). The antioxidant activities of the four chemotypes were determined using a 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. The antioxidant activities of the essential oil decreased in the order of cinnamyl acetate > cinnamaldehyde > β-cubebene > linalool. Indigenous cinnamon oil extract showed a good free radical-scavenging capacity at all concentrations studied, except at 2 μg/ml. The scavenging activity increased with increasing concentration of the extract. The capability of the four essential oil chemotypes to reduce the stable radical, DPPH, to DPPH-H was assayed by a decrease in the IC₅₀ values of 10.4 (cinnamyl acetate type) to 29.7 (linalool type) μg/ml. These results suggest that the leaf essential oil of C. osmophloeum possesses chemical compounds with antioxidant activity which can be used as natural preservatives in food and/or by the pharmaceutical industry. Trees in this plantation which can be used for further propagation for the production of chemotypes of interest were identified.     

In vitro and in vivo antifungal activities of the essential oils of various plants against tomato grey mould disease agent Botrytis cinerea

The aim of this study was to find an alternative to synthetic fungicides currently used in the control of devastating fungal pathogen Botrytis cinerea, the causal agent of grey mould disease of tomato. Antifungal activities of essential oils obtained from aerial parts of aromatic plants, which belong to the Lamiacea family such as origanum (Origanum syriacum L. var. bevanii), lavender (Lavandula stoechas L. var. stoechas) and rosemary (Rosmarinus officinalis L.), were investigated against B. cinerea. Contact and volatile phase effects of different concentrations of the essential oils were found to inhibit the growth of B. cinerea in a dose-dependent manner. Volatile phase effects of essential oils were consistently found to be more effective on fungal growth than contact phase effect. A volatile vapour of origanum oil at 0.2 μg/ml air was found to completely inhibit the growth of B. cinerea. Complete growth inhibition of pathogen by essential oil of lavender and rosemary was, however, observed at 1.6 μg/ml air concentrations. For the determination of the contact phase effects of the tested essential oils, origanum oil at 12.8 μg/ml was found to inhibit the growth of B. cinerea completely. Essential oils of rosemary and lavender were inhibitory at relatively higher concentrations (25.6 μg/ml). Spore germination and germ tube elongation were also inhibited by the essential oils tested. Light and scanning electron microscopic (SEM) observations revealed that the essential oils cause considerable morphological degenerations of the fungal hyphae such as cytoplasmic coagulation, vacuolations, hyphal shrivelling and protoplast leakage and loss of conidiation. In vivo assays with the origanum essential oil, being the most efficient essential oil, under greenhouse conditions using susceptible tomato plants resulted in good protection against grey mould severity especially as a curative treatment. This study has demonstrated that the essential oils are potential and promising antifungal agents which could be used as biofungicide in the protection of tomato against B. cinerea.     

植物复合精油对5种稻谷霉变优势菌株抑菌作用研究

为了研究天然植物精油(百里香、丁香、肉桂)对霉变稻谷的抑菌效果,以5种稻谷霉变优势菌株为受试菌,以霉菌抑菌圈直径大小和最低抑菌浓度（MIC）为指标,通过混料设计方法建立复合精油抑菌模型,结合方差分析得到抑菌效果最佳的植物精油配比。研究结果表明,单一精油抑菌活性对亮白曲霉（A. candidus）,杂色曲霉（A. versicolor）和聚多曲霉（A. sydowii）为肉桂精油>丁香精油>百里香精油;对稻黑孢霉（N. oryzae）为肉桂精油=丁香精油>百里精香油;对布罗克青霉菌（P. brocae）为丁香精油=百里香精油<肉桂精油。当肉桂精油:丁香精油:百里香精油的体积比为55.2%︰26.9%︰17.9%时,3种植物精油对5种菌株抑制效果最佳,复合抑制值大于90.9%。     

Antimicrobial efficacies of essential oils/nanoparticles incorporated polylactide films against L. monocytogenes and S. typhimurium on contaminated cheese

Polylactide based films were formulated by incorporating polyethylene glycol, selected nanopowders (zinc oxide, silver-copper), and essential oils (cinnamon, garlic, and clove) by solvent casting method. Films were tested against three foodborne pathogens (one gram-positive and two gram-negative) for their antibacterial activity. The effectiveness of selected cinnamon oil-based film was ascertained by performing a challenge test with cheese as a food model. In vitro antibacterial efficacies of nanopowders and essential oils were also determined by the decimal reduction concentrations and the minimum bactericidal concentrations for those foodborne pathogens. It was observed that nanopowders exhibited considerably poorer decimal reduction concentrations and minimum bactericidal concentration values in comparison to the essential oils. Silver-copper alloy nanopowders exhibited lower decimal reduction concentrations and minimum bactericidal concentrations values than ZnO against tested pathogens whereas essential oils showed distinct antimicrobial effectiveness against all those pathogens with in vitro decimal reduction concentration values of 87–157 and 77–220 µg/mL for cinnamon and clove oils, respectively. Among the various formulations, it was observed that only essential oils (especially cinnamon and clove) incorporated films exhibited a significant antimicrobial activity against the selected microorganisms. These results indicate that the poor antibacterial activity of the nanopowders and the hydrophobicity of polylactide could be responsible for the ineffectiveness of nanopowders in polylactide based films. Furthermore, the challenge test indicated the polylactide/polyethylene glycol/cinnamon oil film was appropriate to inhibit the growth of L. monocytogenes and S. typhimurium on cheese up to 11 days at refrigerated storage.     

The antioxidant status and oxidative stability of muscle from lambs receiving oral administration of Artemisia herba alba and Rosmarinus officinalis essential oils

The effect of the dietary supplementation to lambs of essential oils (EOs) from rosemary (Rosmarinus officinalis) and artemisia (Artemisia herba alba) on the antioxidant status of muscle and on meat oxidative stability was studied. Eighteen Barbarine lambs were divided into 3 groups and for 95 days received oat hay and concentrates. One group (C) was not supplemented, while the other two groups received 400 mg/kg of EOs from rosemary (R400) or artemisia (A400). Both EOs possessed antioxidant properties and their oral administration improved the reducing and radical scavenging capacity of the muscle compared to the C treatment (P < 0.01). Nevertheless, supplementing EOs did not exert protection against lipid oxidation and did not affect the colour stability in meat over 7 days of aerobic storage.     

Comparison of essential oils of clove buds extracted with supercritical carbon dioxide and other three traditional extraction methods

Supercritical fluid extraction (SFE) of essential oil from clove buds with CO₂ was explored. The effect of different parameters, such as temperature (30 °C, 40 °C, 50 °C), pressure(10 MPa, 20 MPa, 30 MPa) and particle size (three degree index), on the extraction yield and the content of eugenol in extracts was investigated using three-level orthogonal array design. The experimental results show that the temperature has the largest effect on the eugenol content of the extracts, and particle size has the maximum effect on the oil yield. The essential oil of 19.56% yield, in which the maximum content of eugenol in extracts is 58.77%, can be extracted from clove buds at pressure of 10 MPa and temperature of 50 °C. Essential oil of clove buds obtained by SFE, hydrodistillation, steam distillation and Soxhlet extraction were further analyzed by gas chromatography/mass spectrometric detection to compare the extraction methods. Twenty three compounds in the clove oils have been identified, showing that the composition of the clove oil extracted by different methods is mostly similar, whereas relative concentration of the identified compounds is apparently different. General characteristics of the clove oils obtained by different methods were further compared, and SFE is considered as the optimum process among the four processes for obtaining clove oil with high quality.     

Antibacterial activity of 11 essential oils against Bacillus cereus in tyndallized carrot broth

The antibacterial activity of 11 essential oils from aromatic plants against the strain INRA L2104 of the foodborne pathogen Bacillus cereus grown in carrot broth at 16 degrees C was studied. The quantity needed by the essential oils of nutmeg, mint, clove, oregano, cinnamon, sassafras, sage, thyme or rosemary to produce 14-1110% relative extension of the lag phase was determined. Total growth inhibition of bacterial spores was observed for some of the antimicrobial agents assayed. The addition of 5 microl cinnamon essential oil per 100 ml of broth in combination with refrigeration temperatures of 相似文献   

Insecticidal activities of aromatic plant extracts and essential oils against Sitophilus oryzae and Callosobruchus chinensis

Methanol extracts from 30 aromatic medicinal plant species and five essential oils were tested for their insecticidal activities against adults of Sitophilus oryzae (L.) and Callosobruchus chinensis (L.), using direct contact application and fumigation methods. Responses varied with plant material, insect species, and exposure time. In a test with a filter paper diffusion method at 3.5 mg/cm², potent insecticidal activity against both species was produced by an extract from Cinnamomum cassia bark, cinnamon (C. cassia) oil, horseradish (Cocholeria aroracia) oil, and mustard (Brassica juncea) oil within 1 day after treatment. Over 90% mortality at 3 or 4 days after treatment was achieved using extracts of Acorus calamus var. angustatus rhizome, Acorus gramineus rhizome, Illicium verum fruit, and Foeniculum vulgare fruit. An extract from Cinnamomum sieboldii root bark gave 100% mortality at 2 days after treatment. At 0.7 mg/cm², extracts from C. cassia, C. sieboldii, and F. vulgare as well as cinnamon oil, horseradish oil and mustard oil were highly effective against both species. In a fumigation test with S. oryzae adults, the oils described were much more effective in closed containers than in open ones, indicating that the insecticidal activity of the oils was attributable to fumigant action. The plant extracts and essential oils described could be useful for managing field populations of S. oryzae and C. chinensis.     

Application of plant essential oils in prevention of fungal growth on Para rubber wood

Antifungal activities of essential oils (cinnamon, clove, eucalyptus, peppermint and lemongrass oils) against moulds (Penicillium sp., Aspergillus niger and Aspergillus versicolor) isolated from rubber wood surfaces were examined. Clove oil possessed consistent antifungal activity with the minimal inhibitory concentration (MIC) of 5 μl ml^?1 against all these fungi, while cinnamon oil had MICs from 2.5 to 10 μl ml^?1. However, only dip treatment with cinnamon oil inhibited the growth of A. niger on rubber wood for at least 25 weeks.     

Effects of essential oils and oleoresins of plants on ethanol production,respiration and sporulation of yeasts

Ethanol production, respiration, and sporulation of yeasts as effected by essential oils and oleoresins of allspice, cinnamon, clove, garlic, onion, oregano, savory, and thyme were investigated. Essential oils of allspice, cinnamon, and clove had little or no effect on ethanol production by Sacchraromyces cerevisiae. Oils of onion, oregano, savory, and thyme delayed and/or reduced the production of ethanol. Overall, essential oils effectively suppressed ethanol production by Hansenula anomala. At the highest concentrations tested (500 μg/ml), only cinnamon, clove, garlic and thyme oleoresins substantially delayed and/or reduced ethanol production by S. cerevisiae. Most of the essential oils (100 μm/ml) impaired the respiratory activity of S. cerevisiae as evidenced by a reduction in CO₂ production. Thyme oleoresin was the strongest inhibitor. Allspice and garlic oils impaired sporulation by H. anomala. All oils delayed sporulation of Lodderomyces elongisporus).     

The potential application of plant essential oils as natural food preservatives in soft cheese

Investigations were carried out to assess the efficiency of four plant essential oils; bay, clove, cinnamon and thyme as natural food preservatives. The effect of the plant essential oils at concentrations of 0·1, 0·5 and 1% was studied in low-fat and full-fat soft cheese against Listeria monocytogenes and Salmonella enteritidis at 4° and 10°C respectively, over a 14-day period. The composition of the cheese was shown to be an important factor in determining the effectiveness of the plant essential oils. In the low-fat cheese, all four oils at 1% reduced L. monocytogenes to ≤1·0 log₁₀cfu ml⁻¹. In contrast, in the full-fat cheese, oil of clove was the only oil to achieve this reduction. Oil of thyme proved ineffective against S. enteritidis in the full-fat cheese, yet was equally as effective as the other three oils in the low-fat cheese, reducing S. enteritidis to ≤1·0 log₁₀cfu ml⁻¹from day 4 onwards. It is concluded that selected plant essential oils can act as potent inhibitors of L. monocytogenes and S. enteritidis in a food product.     

Chemical composition,antioxidant and antibacterial activities of the essential oils isolated from Tunisian Thymus capitatus Hoff. et Link.

The chemical composition, antioxidant and antibacterial activities of essential oils isolated by hydrodistillation from the aerial parts of Tunisian Thymus capitatus Hoff. et Link. during the different phases of the plant development, and from different locations, were evaluated. The chemical composition was analyzed by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). The main components of the essential oils were carvacrol (62–83%), p-cymene (5–17%), γ-terpinene (2–14%) and β-caryophyllene (1–4%). The antioxidant activity of the oils (100–1000 mg l⁻¹) was assessed by measurement of metal chelating activity, the reductive potential, the free radical scavenging (DPPH) and by the TBARS assay. The antioxidant activity was compared with that of synthetic antioxidants: butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). Both the essential oils and BHA and BHT showed no metal chelating activity. Although with the other methodologies, there was a general increase in the antioxidant activity, with increasing oil concentration, maxima being obtained in the range of 500 and 1000 mg l⁻¹ for flowering and post-flowering phase oils. Major differences were obtained according to the methodology of antioxidant capacity evaluation. Antibacterial ability of Th. capitatus essential oils was tested by disc agar diffusion against Bacillus cereus, Salmonella sp., Listeria innocua, four different strains of Staphylococus aureus (C15, ATCC25923, CFSA-2) and a multi-resistant form of S. aureus (MRSA-2). Antibacterial properties were compared to synthetic antibiotics. Higher antibacterial activity was observed with the flowering and the post-flowering phase essential oils.     

Effect of essential oils of cinnamon,clove, lemon grass,oregano and palmarosa on growth of and fumonisin B1 production by Fusarium verticillioides in maize

The ability of cinnamon, clove, lemon grass, oregano and palmarosa essential oils to prevent growth of and fumonisin B₁ (FB₁) production by Fusarium verticillioides at different water activity (0.95 and 0.995 a_w) and temperature (20 and 30 °C) levels in irradiated maize grain was evaluated. All the essential oils inhibited growth of F verticillioides isolates under all conditions tested, but FB₁ production was only inhibited at 30 °C and 0.995 a_w. Moreover, stimulation of toxin production was found under certain environmental conditions. None of the essential oils showed a significantly greater ability to inhibit FB₁ production when compared with the others. At 1000 mg essential oil kg^?1 maize the essential oils showed a greater inhibitory effect on growth of F verticillioides than at 500 mg kg^?1, but there was no difference in FB₁ production between the two levels of essential oil. Copyright © 2004 Society of Chemical Industry     

Chemical and biological characteristics of Cuminum cyminum and Rosmarinus officinalis essential oils

Essential oils extracted by hydrodistillation from Cuminum cyminum and Rosmarinus officinalis were characterized by means of GC and GC–MS. C. cyminum and R. officinalis contained α-pinene (29.1%, 14.9%), 1,8-cineole (17.9%, 7.43%) and linalool (10.4%, 14.9%), respectively, as the major compounds. C. cyminum oil exhibited stronger antimicrobial activity than did R. officinalis oil against E. coli, S. aureus and L. monocytogenes. Complete death time on exposure to Cuminum cyminum L. and Rosmarinus officinalis L. oils were 20 and 25 min 180 and 240 min and 90 and 120 min for E. coli, S. aureus and L. monocytogenes, respectively. Radical-scavenging and antioxidant properties were tested by means of 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay and the β-carotene bleaching test. These properties were compared to those of Thymus x-porlock essential oil, used as a reference ingredient. The radical scavenging performance of the rosemary oil was better than that of C. cyminum. Results from the antioxidant test were better than those provided by the radical-scavenging activity. C. cyminum and R. officinalis essential oils may be considered as potent agents in food preservation.     

Antifungal activity of five different essential oils in vapour phase for the control of Colletotrichum gloeosporioides and Lasiodiplodia theobromae in vitro and on mango

Mango fruit has high commercial value; however, major postharvest losses are encountered throughout the supply chain due to postharvest diseases. These results lead to the search for natural fungicide for postharvest diseases control. The antifungal effects of five essential oils (thyme, clove, cinnamon, anise and vitex) were assessed by disc volatilisation method. Thyme oil vapours at 5 μL per Petriplate, and clove and cinnamon oil at 8 μL per Petriplate showed 100% growth inhibition of mango pathogens in vitro. GC/MS analysis of essential oil showed thymol (23.88), o‐cymol (23.88) and terpinolene (23.88) as the major constituents of thyme oil. Clove and cinnamon oils contain 3‐allyl‐2‐methoxyphenol (37.42%) and benzofuran 3‐methyl (17.97%), respectively. Thyme oil as a fumigant at 66.7 μL L^?1 showed a significant (P < 0.05) inhibition on postharvest pathogens of mango fruits stored at 25 °C for 6 days. Results of our study suggest the possibility of using thyme oil as an alternate natural fungicide to manage postharvest diseases in mango.     

An integrated strategy to control post-harvest decay of Embul banana by combining essential oils with modified atmosphere packaging

Mature Embul (Musa, AAB) bananas were treated with emulsions of either cinnamon bark or leaf (Cinnamomum zeylanicum) or clove (Syzygium aromaticum) oils to control post‐harvest diseases, packed under modified atmosphere (MA) using low‐density polyethylene (0.075 mm, LDPE) bags, and stored in a cold room (14 ± 1 °C, 90% RH) or at ambient temperature (28 ± 2 °C). The effects of the essential oils on post‐harvest diseases; physico‐chemical properties and organoleptic properties were determined and compared with controls and bananas treated with benomyl. Treatments with cinnamon bark and leaf oils controlled crown rot, whereas clove oil treatment did not affect crown rot development. Treatment with emulsions of cinnamon oils combined with MA packaging can be recommended as a safe, cost‐effective method for extending the storage life of Embul bananas up to 21 days in a cold room and 14 days at 28 ± 2 °C without affecting the organoleptic and physico‐chemical properties.     

Properties and antioxidant activity of fish skin gelatin film incorporated with citrus essential oils

Properties of protein-based film from fish skin gelatin incorporated with different citrus essential oils, including bergamot, kaffir lime, lemon and lime (50% based on protein) in the presence of 20% and 30% glycerol were investigated. Films containing 20% glycerol had higher tensile strength (TS) but lower elongation at break (EAB), compared with those prepared with 30% glycerol, regardless of essential oils incorporated (p < 0.05). Films incorporated with essential oils, especially from lime, at both glycerol levels showed the lower TS but higher EAB than the control films (without incorporated essential oil) (p < 0.05). Water vapour permeability (WVP) of films containing essential oils was lower than that of control films for both glycerol levels (p < 0.05). Films with essential oils had varying ΔE^* (total colour difference), where the highest value was observed in that added with bergamot essential oil (p < 0.05). Higher glycerol content increased EAB and WVP but decreased TS of films. Fourier transforms infrared (FTIR) spectra indicated that films added with essential oils exhibited higher hydrophobicity with higher amplitude at wavenumber of 2874–2926 cm⁻¹ and 1731–1742 cm⁻¹ than control film. Film incorporated with essential oils exhibited slightly lower thermal degradation resistance, compared to the control film. Varying effect of essential oil on thermal degradation temperature and weight loss was noticeable, but all films prepared using 20% glycerol had higher thermal degradation temperature with lower weight loss, compared with those containing 30% glycerol. Films added with all types of essential oils had rough cross-section, compared with control films, irrespective of glycerol levels. However, smooth surface was observed in all film samples. Film incorporated with lemon essential oil showed the highest ABTS radical scavenging activity and ferric reducing antioxidant power (FRAP) (p < 0.05), while the other films had lower activity. Thus, the incorporation of different essential oils and glycerol levels directly affected the properties of gelatin-based film from fish skin.     

Contact and fumigant activities of aromatic plant extracts and essential oils against Lasioderma serricorne (Coleoptera: Anobiidae)

Methanol extracts from 30 aromatic medicinal plant species and five plant essential oils were tested for their insecticidal activities against Lasioderma serricorne (F.) adults using direct contact application and fumigation methods. Responses varied with plant material and exposure time. Good insecticidal activity against L. serricorne adults was achieved with extracts of Agastache rugosa whole plant, Cinnamomum cassia bark, Illicium verum fruit and Foeniculum vulgare fruit as well as cinnamon (C. cassia), horseradish (Cocholeria aroracia) and mustard (Brassica juncea) oils applied at 3.5 mg/cm² in a filter paper diffusion method. Over 90% mortality at 3 days after treatment was achieved with an extract of Acorus calamus var. angustatus rhizome. Cinnamon, horseradish and mustard oils, at 0.7 mg/cm², were highly toxic to the adult beetles 1 day after treatment. In a fumigation test with the beetle adults, insecticidal activity of horseradish oil, mustard oil and Foeniculum fruit extract was much more effective in closed cups than in open ones, indicating that the insecticidal activity of these materials was largely attributable to fumigant action. These naturally occurring plant extracts and essential oils could be useful for managing populations of L. serricorne.     

The effects of thyme (Thymus vulgaris) and rosemary (Rosmarinus officinalis) essential oils on Brochothrix thermosphacta and on the shelf life of beef packaged in high-oxygen modified atmosphere

The objective of the study was to determine the Minimal Inhibitory Concentration (MIC) of thyme (29.4% thymol, 21.6% p-cymene) and rosemary essential oils (27.6% 1,8-cineole, 13.5% limonene, 13.0% β-pinene) against Brochothrix thermosphacta and to establish the feasibility of their use as components of modified atmosphere during beef refrigerated storage. The minimum inhibitory concentration (MIC) of thyme oil against B. thermosphacta is 0.05% and that of rosemary oil 0.5%. The MIC values are independent on strain and temperature of growth, however the bactericidal effects are strain dependent. The addition of any of oil at a concentration equal to 2MIC to the modified atmosphere (80% O₂/20% CO₂) does not significantly influence the microbial quality of meat. At the same time, such a concentration of the essential oils was considerably detrimental to the organoleptic factors.